IB Diploma Biology Practice Test 2026 - Free Biology Exam Practice Questions and Study Guide

During osmosis, water molecules move from an area of high water concentration (which corresponds to a low solute concentration) to an area of low water concentration (which corresponds to a high solute concentration). This movement continues until equilibrium is reached, where the concentration of water is equal on both sides of the membrane. This process is driven by the tendency of solvent molecules to dilute solute concentrations, and it primarily occurs through semi-permeable membranes that allow water, but not solutes, to pass through.

This phenomenon plays a crucial role in biological systems, maintaining cell turgor pressure and regulating the internal environment of cells. Understanding osmosis is fundamental in contexts such as plant water uptake, kidney function, and cellular homeostasis.